Utilities

Public utilities are a frequently overlooked element of arterial street design, despite the significant implications their placement, maintenance, and design have on roadway functionality and cost. Both underground and overhead utilities occupy a significant space within the right-of-way. See the attached PDF document for a diagram of utilities.

Utilities which are commonly overhead:

Telephone

Cable television

Overhead lighting

Electricity

Utilities which are typically underground:

Water

Natural gas

Irrigation (sprinkler systems

Sanitary sewer

Storm sewer

The poles used to support overhead utilities can present a roadside safety risk in some corridors. Specifically, 10 percent of all fatal, fixed-object crashes are a result of motor vehicle collisions with utility poles supporting overhead utility lines. If utilities must be overhead, it is imperative that the poles and cabinets are located in the areas where they are least likely to be struck by an errant vehicle. AASHTO’s Roadside Design Guide offers several design considerations for maximizing safety when roadside overhead utilities are present.

Locate power and telephone lines underground, whenever possible. Burying these lines can be costly, especially in retrofit situations but the improvement in safety, appearance, and mobility for pedestrians is worth it.

Maximize the lateral distance between the vehicular travel way and utility poles. AASHTO recommends a minimum of 18 inches between the back of the curb and the roadway. The resulting tradeoff is that the utilities are then closer to building frontages.

Reduce the number of utility poles along the street. Maximize the spacing between utility poles and whenever possible, combine multiple utilities on a single pole (e.g. combine overhead lighting with a traffic signal and perhaps even a power line).

Use a breakaway pole design. This will minimize the impact and severity of collisions.

Preserve pedestrian walkway. Overhead utilities significantly affect the character of the streetscape. In addition to being unsightly, above ground utility poles are often located along or even in the middle of the sidewalk, encroaching on the pedestrian walkway. The clear pedestrian walkway should be a minimum of five feet wide, even when poles are present. In downtown areas sidewalks should be wider to accommodate high volumes of pedestrian traffic and pedestrians using mobility aids.

Consider maintenance of utilities in the planning process. Utility maintenance (overhead or underground) should be considered when locating utilities and other roadside elements such as trees, street furniture, traffic signs, and drainage inlets that could potentially impede or prevent access.

Coordinate early and often. Utility coordination is an essential component of the planning and design of great streets. Most streets have a number of utilities, each of which may be owned and managed by a different agency. Frequent and early coordination with these agencies can save time and money, especially when service lines are being upgraded or relocated. Coordination between roadway planners and utility agencies can improve design and lower the costs associated with roadway construction or improvements. The agency responsible should understand utility plans for the corridor and provide the appropriate utility companies with street design plans early in the process to solicit comments. Close coordination can also minimize impacts associated with construction, particularly for adjacent property owners.

Credit: CH2M HILL

Locate utilities before making improvements to an existing roadway. A thorough subsurface utility investigation should be performed before beginning work on retrofit projects to avoid discovering unexpected utility lines, and the associated costs and setbacks.

Existing plans or “as builts” can be used in combination with detection technologies such as ground penetrating radar to identify unrecorded underground utility lines along a corridor. A relatively small investment of time and money early in the planning stage can help minimize unanticipated costs during construction.

Improve the aesthetics of utilities through design, signage, lighting, and seasonal decorations. There are a variety of simple, innovative ways to transform utility hardware into attractive streetscape enhancements. For example, ordinary traffic signal cabinets can be decorated with colorful, artistic murals linking the street to the surrounding land uses, as shown in the images below. Other improvements to utility infrastructure can involve partnerships with local businesses and residents to provide and maintain amenities, such as flowers and plants, lights and decorations. Involvement by citizens and local businesses can reduce costs, enhance community buy-in, and build mutual interest in creating and maintaining great streets.